This is my third summer with this tree. I purchased it in 2013 at a nursery at which point I cut it back and re-potted it.

Didn't do much last summer. It's due for re-potting now. Spring came early and it bloomed earlier than I had expected but I still plan on re-potting soon although I would have preferred to do so before the buds opened.

I was going to prune it a lot this spring, but a friendly rabbit took care of that over the winter (which is why the right side looks more compact). Thank you Mr. Rabbit. I will prune the two long branches on left side next year.

What do you think so far? All in all it's about a 1.5 feet tall from the base of the trunk to the top of the trunk.

Does the water drain fairly quickly and not pool on the surface? If you have good drainage, why repot? I usually don't say this, but...a good low chop on this and you got a start on a great tree. Think about a final height of maybe 9 to 10 inchs. 22 - 23 cm's? Nice color, love maples, all kinds!!

I'm a LOOOONG way from Quebec, but I wouldn't repot unless it is necessary for some reason, such as the health of the tree -- and that obviously is not the reason. It is planted in a basked, so the root will be self pruning if they poke through (and I see none).

I think I would prune it more -- even on the rabbit side.

Then, just feed and water for another growing season and repot next year as the buds are swelling.

Look like it will turn into a nice bonsai.

_________________Jim Lewis - lewisjk@windstream.net - Western NC - People, when Columbus discovered this country, it was plumb full of nuts and berries. And I'm right here to tell you the berries are just about all gone. Uncle Dave Macon, old-time country musician

I'm not too fond of having used a pond basket because it dries out fairly quickly later in the summer which scares me when I have to go out of town for more than 2-3 days

On those occasions, put it on the ground, in a box with wet shredded newspaper in it and in FULL shade.

Or, for slightly longer periods, put it in a box, fill the box around it with fine sand (builder's sand), saturate the sand with water -- again in FULL shade to reduce transpiration.

_________________Jim Lewis - lewisjk@windstream.net - Western NC - People, when Columbus discovered this country, it was plumb full of nuts and berries. And I'm right here to tell you the berries are just about all gone. Uncle Dave Macon, old-time country musician

Looks good after pruning. I would probably start cutting the long shoots back to a single pair of leaves to develop some ramification options. You will typically get 2 or 3 good flushes of growth that can be cut back to a pair of leaves during the summer with a strong Amur Maple. This will also reduce the leaf size.

The only reasons to let them run wild are to fatten up a branch or to strengthen the roots after repotting. I don't see either as an issue here, but there may be a low branch or two we can't see that needs to fatten up.

I have one that is a bit smaller (a triple trunk) and I am even pruning out the central stalk as the leave open to improve ramification. It is growing in a fairly wide shallow pot (depth is the 3 cm trunk diameter and width is the 25 cm or so. Amur will take fairly severe root pruning and grow well in a shallow bonsai pot. Given that this one has been in the rather deep basket for 3 years, I suggest reducing the root ball depth by 50-60% next year and continuing to reduce it to get it into a proper pot at each replanting. If if grows strongly after repotting, you can repot the next year. I don't repot mine too often to try to contain the growth. A shallow pot will dry even faster than the basket so Jim's comments on travel are even more valid.

I would prune it now. I would buy a larger version of the basket pot you have it in and plant the tree STILL IN THE EXISTING POT in the larger pot and keep it well fed and watered to help encourage growth. This will let the roots grow through the holes in the existing pot and into the new space created by the bigger pot, then just before next spring I'd dismantle the double pot assembly, trim the roots and repot into a wider shallower container or on a large tile in the ground to fatten the trunk if it requires it.

By the way - I use an automatic watering system if I'm away - and haven't lost a tree whilst doing so in the last 10 years since I started doing it. A fairly inexpensive outside tap mounted timer and a hose with a lawn sprinkler head on the end of it works very well.

I am also now planting all my developing small trees in pond baskets as they have done so well in them. The UK climate is fairly friendly for that however - it might not be the same in hotter or colder places.